JP2784439B2 - Magnetoresistance storage element, array and device - Google Patents

Magnetoresistance storage element, array and device

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Publication number
JP2784439B2
JP2784439B2 JP6022669A JP2266994A JP2784439B2 JP 2784439 B2 JP2784439 B2 JP 2784439B2 JP 6022669 A JP6022669 A JP 6022669A JP 2266994 A JP2266994 A JP 2266994A JP 2784439 B2 JP2784439 B2 JP 2784439B2
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Japan
Prior art keywords
storage element
layer
magnetization
ferromagnetic
cell
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JPH06295419A (en
Inventor
ケニス・ティン＝ユアン・クン
デニー・ドゥアン＝リー・タン
ワン・ポー・カン
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International Business Machines Corp
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International Business Machines Corp
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G11C11/161—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G11C11/165—Auxiliary circuits
    • G11C11/1673—Reading or sensing circuits or methods
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G11C11/165—Auxiliary circuits
    • G11C11/1675—Writing or programming circuits or methods

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  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Mram Or Spin Memory Techniques (AREA)
  • Semiconductor Memories (AREA)
  • Hall/Mr Elements (AREA)
  • Magnetic Heads (AREA)

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本発明は、高性能非揮発性記憶装
置に関し、より詳しくは、スピン・バルブ構成を持つ磁
気抵抗記憶素子を使用する非揮発性磁気ランダム・アク
セス記憶装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high performance nonvolatile storage device, and more particularly to a nonvolatile magnetic random access storage device using a magnetoresistive storage element having a spin valve structure.

【０００２】[0002]

【従来の技術】本発明者等は、以下の参照文献を本発明
に関連が最も深いと考える。BACKGROUND OF THE INVENTION The present inventors consider the following references to be most relevant to the present invention.

【０００３】［Ａ］米国特許第５１５９５１３号は、ス
ピン・バルブ効果を利用した磁気抵抗（ＭＲ）センサを
開示している。このセンサは、ガラスまたはその他の適
切な基板上に付着された長方形の多層構造を備えてい
る。第１および第２の強磁性層が、薄い銅製のスペーサ
層によって分離されている。第１の層の磁化は、硬磁気
材料を第１の層として使用することによって、あるい
は、それが好ましいなら反強磁性層を使用して交換結合
により第１の層を固定することによって、センサの幅に
直交する方向に固定されている。第２の層の磁化は、通
常センサの長さに沿った方向であるが、感知される磁界
の大きさによって決定される角度で自由に回転すること
ができる。したがって、このセンサはアナログ型装置で
ある。[A] US Pat. No. 5,159,513 discloses a magnetoresistive (MR) sensor utilizing the spin valve effect. The sensor comprises a rectangular multilayer structure deposited on a glass or other suitable substrate. The first and second ferromagnetic layers are separated by a thin copper spacer layer. The magnetization of the first layer is determined by using a hard magnetic material as the first layer, or by pinning the first layer by exchange coupling using an antiferromagnetic layer if that is preferred. Is fixed in a direction orthogonal to the width of The magnetization of the second layer is usually in the direction along the length of the sensor, but is free to rotate at an angle determined by the magnitude of the magnetic field to be sensed. Thus, the sensor is an analog device.

【０００４】［Ｂ］American Physical Society、Vol.3
9、 No.7、 p.4828(1989年)に発表された"Enhanced Magne
toresistance in Layered Magnetic Structures With A
ntiferromagnetic Interlayer Exchange"と題する論文
では、これらの層の間の反強磁性結合によって、強磁性
膜層中で磁化が反平行に整列するため、磁気抵抗効果が
大幅に増大するので、ＭＲ磁界センサなどの応用例にと
って魅力的であると指摘している。[B] American Physical Society, Vol.3
9, No. 7, p. 4828 (1989) "Enhanced Magne
toresistance in Layered Magnetic Structures With A
In the paper entitled "ntiferromagnetic Interlayer Exchange", the antiferromagnetic coupling between these layers causes the magnetization to be aligned antiparallel in the ferromagnetic film layer, greatly increasing the magnetoresistance effect. It is attractive for applications.

【０００５】［Ｃ］J. Appl. Physics、69(8)、(1991年4
月15日、 p.5760以降)に発表された"Memory Implication
s of the Spin-Valve Effect in Soft Multilayers"と
題する論文は、以下でさらに詳細に説明するいくつかの
欠陥も持つＭＲ記憶素子を記載している。[C] J. Appl. Physics, 69 (8), (1991, 4
On March 15, p.5760) "Memory Implication"
A paper entitled "s of the Spin-Valve Effect in Soft Multilayers" describes an MR storage element that also has some deficiencies, which are described in further detail below.

【０００６】[0006]

【発明が解決しようとする課題】本発明の目的はこれら
の欠陥を解決する次のような非揮発性磁気記憶装置を提
供することにある。 （１）状態照会（state interrogation）を必要とせず
に直流読取りを実行する。状態照会は読取り信号と同義
であり、その状態が"１"か"０"を決定する。 （２）磁気層の全（full）δＲ／Ｒ（すなわち、利用可
能なδＲ／Ｒ）を使用して、高感度を実現する。 （３）ロックイン検出を不要にすることによって読取り
アクセス時間を改善する。ロックイン検出は長期間にわ
たり平均化する反復信号である。（この信号が小さいと
きは、ノイズにより検出が困難であるので、多数回にわ
たり読取りが行なわれるとともに、"それをロックイン"
して平均化がなされる。） （４）主として、ＭＲ記憶素子の幅を短縮することによ
ってスピン・バルブ・セルのサイズを縮小できるように
し、信号レベルを上げる。 （５）高速の書込み動作および消去動作を可能にする。SUMMARY OF THE INVENTION An object of the present invention is to provide a nonvolatile magnetic memory device which solves these defects as follows. (1) Perform DC reading without the need for state interrogation. The status inquiry is synonymous with the read signal and determines whether the status is "1" or "0". (2) High sensitivity is achieved using the full δR / R of the magnetic layer (ie, available δR / R). (3) Improve read access time by eliminating the need for lock-in detection. Lock-in detection is a repetitive signal that averages over time. (When this signal is small, it is difficult to detect due to noise, so it is read many times and "lock it in."
Averaging is then performed. (4) Mainly, by reducing the width of the MR storage element, the size of the spin valve cell can be reduced, and the signal level is increased. (5) Enable high-speed write and erase operations.

【０００７】[0007]

【課題を解決するための手段】基板と、非磁性金属材料
層によって分離された２つの強磁性材料層を含む、基板
に付着された長方形の多層構造とを備えた非揮発性磁気
抵抗記憶素子が記述される。両方の強磁性層の磁化容易
軸は、記憶素子のほぼ長さ方向に配向している。一方の
強磁性層の磁化は、記憶素子のほぼ長さ方向である１つ
の方向に固定され、他方の強磁性層の磁化は、印加され
る磁界に応じて、固定方向に対してほぼ平行な方向とほ
ぼ反平行な方向との間で自由に変化する。SUMMARY OF THE INVENTION A non-volatile magnetoresistive storage element comprising a substrate and a rectangular multilayer structure attached to the substrate, including two layers of ferromagnetic material separated by a layer of non-magnetic metal material. Is described. The easy axes of the two ferromagnetic layers are oriented substantially in the length direction of the storage element. The magnetization of one ferromagnetic layer is fixed in one direction, which is substantially the length direction of the storage element, and the magnetization of the other ferromagnetic layer is substantially parallel to the fixed direction depending on the applied magnetic field. It changes freely between the direction and a direction substantially parallel to the anti-parallel.

【０００８】記憶素子の幅は、多層構造の層の磁壁の幅
より短い。[0008] The width of the storage element is shorter than the width of the domain wall of the layer of the multilayer structure.

【０００９】印加される磁界は、強磁性層の磁化方向が
平行であるか反平行であるかによって、記憶素子をそれ
ぞれ論理"１"または論理"０"を表す２つの状態の間で切
り替える。一方の強磁性層の磁化方向は、反強磁性層と
の交換結合によって固定することができる。あるいは、
それが好ましければ、前記他方の層の保磁力よりも大き
な保磁力または十分に大きな異方性を持つ硬磁性材料を
一方の層に使用して、状態切替え動作時にその磁化を保
持することもできる。The applied magnetic field switches the storage element between two states representing logic "1" or logic "0", respectively, depending on whether the magnetization directions of the ferromagnetic layers are parallel or anti-parallel. The magnetization direction of one ferromagnetic layer can be fixed by exchange coupling with the antiferromagnetic layer. Or,
If it is preferable, a hard magnetic material having a coercive force larger than the coercive force of the other layer or a sufficiently large anisotropy is used for one layer to retain its magnetization during the state switching operation. Can also.

【００１０】[0010]

【実施例】図１および２は、参照文献［Ｃ］に記載され
た種類のＭＲ記憶素子を示す。このＭＲ記憶素子は、薄
い非磁性スペーサ層１４によって分離された２つの強磁
性層１１、１２を備えている。強磁性層１１、１２の磁
化方向は矢印１５、１６（図１）で示すように反平行で
あり、これらの磁化方向がどちらも、矢印１７、１８
（図２）で示すように書込み電流に応じてほぼ１８０°
変化し、磁化容易軸異方性は矢印１９で示すセンス電流
の方向に対して垂直であることに留意されたい。1 and 2 show an MR storage element of the kind described in reference [C]. This MR storage element comprises two ferromagnetic layers 11, 12 separated by a thin non-magnetic spacer layer 14. The magnetization directions of the ferromagnetic layers 11 and 12 are antiparallel as shown by arrows 15 and 16 (FIG. 1), and both of these magnetization directions are arrows 17 and 18.
As shown in FIG. 2, almost 180 ° according to the write current
Note that the variable easy axis anisotropy is perpendicular to the direction of the sense current indicated by arrow 19.

【００１１】この２つの磁気状態は同じ直流出力を与え
るので、ＭＲ記憶装置に動的に照会して既存の状態を決
定するためには、書込み／照会電流１３によって提供さ
れる縦方向磁界が必要である。読取り時の状態の切替え
の結果、記憶された情報が破壊されるのを防止するため
に、磁化の回転は小さな量しか許されない。このため、
磁気センサ層のδＲ／Ｒが十分に利用できない。Since the two magnetic states provide the same DC output, the longitudinal magnetic field provided by the write / query current 13 is required to dynamically query the MR storage to determine the existing state. It is. Only a small amount of rotation of the magnetization is allowed to prevent the stored information from being destroyed as a result of the switching of states during reading. For this reason,
ΔR / R of the magnetic sensor layer cannot be fully utilized.

【００１２】たとえば、１メガビット・アレイにおい
て、読取り動作中の２つの状態間の回転の差は、０．２
２％のδＲ／Ｒに対応する。この値は、多層構造の２．
５％という総δＲ／Ｒ（すなわち、利用可能なδＲ／
Ｒ）の１０分の１より小さい。また、状態が変化しない
ように、センス電流の大きさを制限する必要がある。For example, in a 1 megabit array, the difference in rotation between the two states during a read operation is 0.2
This corresponds to a δR / R of 2%. This value corresponds to 2.
5% total δR / R (ie, available δR / R
R) less than 1/10. Further, it is necessary to limit the magnitude of the sense current so that the state does not change.

【００１３】δＲ／Ｒの利用が不十分であり、かつセン
ス電流が低いため、感度が低いので、低速の「ロックイ
ン」検出が必要となり、したがって低速の読取りアクセ
ス時間が必要となる。Insufficient utilization of δR / R and low sense current, resulting in low sensitivity, requires slow "lock-in" detection and therefore slow read access time.

【００１４】この構成は、超高密度記憶装置には拡張で
きない。というのは、形状の異方性と磁壁の縁反りのた
めに、磁化の横配向が妨げられるからである。その結
果、記憶素子の幅をあまり狭くすることはできない。ス
ピン・バルブ・セルのサイズを小さくして幅を縮める
と、記憶素子の長さが短くなり、すでに低い信号レベル
がさらに下がる。This configuration cannot be extended to an ultra-high density storage device. This is because the lateral orientation of magnetization is hindered by the shape anisotropy and the warpage of the domain wall. As a result, the width of the storage element cannot be reduced too much. Reducing the size and width of the spin valve cell reduces the length of the storage element, further reducing already low signal levels.

【００１５】これらの欠陥は、本発明者等の新規のスピ
ン・バルブ・セル構成によって解決される。図３および
４に示すように、本発明を実施する記憶素子２０は、ガ
ラス、セラミック、半導体などの適切な基板２２を備え
ており、この基板の上に、第１の軟強磁性材料の薄膜層
２４、銅などの非磁性金属材料の薄膜層２６、および第
２の強磁性材料の薄膜層２８が付着される。[0015] These deficiencies are solved by our novel spin valve cell configuration. As shown in FIGS. 3 and 4, a storage element 20 embodying the present invention includes a suitable substrate 22, such as glass, ceramic, or semiconductor, on which a thin film of a first soft ferromagnetic material is deposited. A layer 24, a thin film layer 26 of a non-magnetic metal material such as copper, and a thin film layer 28 of a second ferromagnetic material are deposited.

【００１６】記憶素子２０が長方形であり、磁化容易軸
が記憶素子の長さに沿っていることに留意されたい。第
２の強磁性層２８の磁化方向は、反強磁性層３０との交
換結合などによって、記憶素子の長さ方向に平行になる
ように固定される（矢印２９を参照）。しかし、第２の
強磁性層２８が状態切替え動作中に磁化を保持するのに
十分な硬磁気材料であるか、または十分な異方性を持つ
場合に限り、それが好ましければ、反強磁性層３０を除
去することができる。Note that the storage element 20 is rectangular and the easy axis is along the length of the storage element. The magnetization direction of the second ferromagnetic layer 28 is fixed to be parallel to the length direction of the storage element by exchange coupling with the antiferromagnetic layer 30 or the like (see arrow 29). However, if the second ferromagnetic layer 28 is of a sufficient hard magnetic material or has sufficient anisotropy during the state switching operation or if it has sufficient anisotropy, The ferromagnetic layer 30 can be removed.

【００１７】第１の軟強磁性層２４の磁化は、一軸異方
性および幾何形状によって、記憶素子２０の長さ方向、
すなわち第２の強磁性層２８の固定磁化方向に平行（図
３の矢印３１を参照）または反平行（図４の矢印３３を
参照）になるように拘束される。記憶素子２０の"１"状
態（図３）と"０"状態（図４）の間での切替えは、記憶
素子２０に横磁界と縦磁界を同時に印加することによっ
て行う。縦磁界は、記憶素子２０の長さ方向に直交して
延びる導体によって提供される書込み線３４中の縦方向
書込み電流３２によって誘導される。横磁界は、記憶素
子２０を通ってその長さ方向に流れる横書込み／センス
電流３６によって誘導される。横磁界を強化することに
よって安定性を増したい場合は、記憶素子２０を通って
その長さ方向に延び、基板２２と第１の軟強磁性層２４
に接触する絶縁層３３との間に挿入される、任意選択の
別個の導体３７によって追加の横書込み／センス電流を
提供することができる。導体３７は、図３だけに示して
ある。The magnetization of the first soft magnetic layer 24, the uniaxial anisotropy and geometry, the longitudinal direction of the storage element 20,
That is, the second ferromagnetic layer 28 is constrained to be parallel (see arrow 31 in FIG. 3) or antiparallel (see arrow 33 in FIG. 4) to the fixed magnetization direction. Switching between the “1” state (FIG. 3) and the “0” state (FIG. 4) of the storage element 20 is performed by simultaneously applying a horizontal magnetic field and a vertical magnetic field to the storage element 20. Vertical magnetic field is induced by longitudinal write current 32 in a write line 34 provided by the conductors extending perpendicular to the longitudinal direction of the storage element 20. The transverse magnetic field is induced by a transverse write / sense current 36 that flows through the storage element 20 in its length direction. If you want to increase stability by strengthening the transverse magnetic field,
The substrate 22 and the first soft ferromagnetic layer 24 extend in the length direction thereof.
An additional lateral write / sense current can be provided by an optional separate conductor 37 inserted between the insulating layer 33 and the contact. The conductor 37 is shown only in FIG.

【００１８】記憶素子２０が２つの２進状態だけを示す
ようにするため、記憶素子２０の短寸法（図３及び図４
の幅Ｗ）を磁壁の幅よりも小さくする必要がある。５０
〜９０Åの典型的なスピン・バルブ厚さでは、ネール壁
の幅が約１．２μｍである。ネール壁は、薄強磁性材料
において２磁区を分ける領域である。ネール壁の幅とは
強磁性薄膜における磁壁の幅となる。これは、記憶素子
２０の幅を１μｍ以下にすれば、状態間の遷移が確実に
なるはずであることを示している。実際の試験で、幅
０．７５μｍの記憶素子では、平行状態と反平行状態の
間で一回の鋭い遷移がもたらされることが分かった。電
気抵抗は、第１の軟強磁性層２４の磁化が固定された第
２の強磁性層２８の磁化に平行であるとき最小となり、
第１の軟強磁性層２４の磁化が固定された第２の強磁性
層２８の磁化と反平行であるとき最大となる。In order for the storage element 20 to show only two binary states, the short dimension of the storage element 20 (FIGS. 3 and 4)
It is necessary to reduce the width W) than the width of the domain wall. 50
At a typical spin valve thickness of Å90 °, the width of the nail wall is about 1.2 μm. The nail wall is an area that separates two magnetic domains in a thin ferromagnetic material. The width of the Neel wall is the width of the domain wall in the ferromagnetic thin film. This indicates that if the width of the storage element 20 is 1 μm or less, the transition between states should be ensured. In actual tests, it has been found that a memory element having a width of 0.75 μm causes one sharp transition between the parallel state and the antiparallel state. The electric resistance is minimized when the magnetization of the first soft ferromagnetic layer 24 is parallel to the magnetization of the fixed second ferromagnetic layer 28,
It becomes maximum when the magnetization of the first soft ferromagnetic layer 24 is antiparallel to the magnetization of the fixed second ferromagnetic layer 28.

【００１９】記憶素子２０のスピン・バルブ・セル構成
が、前述の諸目標を達成することが今や理解できよう。
２つの状態がスピン・バルブ効果による最大および最小
の直流抵抗に対応するので、直流抵抗を検出し、それを
直接読出しに使用することができる。状態の照会は必要
でなく、非破壊読出しが保証される。It can now be seen that the spin valve cell configuration of storage element 20 achieves the goals set forth above.
Since the two states correspond to the maximum and minimum DC resistance due to the spin valve effect, the DC resistance can be detected and used directly for reading. No status inquiry is required and non-destructive read is guaranteed.

【００２０】磁気層２４、２８の総δＲ／Ｒが使用され
る。たとえば、ＮｉＦｅ（９０Å）／Ｃｕ（２０Å）／
ＮｉＦｅ（７０Å）／ＭｎＦｅ（１２０Å）から成り、
δＲ／Ｒが３．６％、Ｒが２０Ω／ｃｍ2である典型的
なスピン・バルブ構造を仮定する。幅１μｍ、長さ５μ
ｍ、センス電流５ｍＡの記憶素子では、信号レベルは約
１８ｍＶである。この値は、高速実時間検出を実行し、
かつ１メガビットの記憶装置で使用するのに十分な程度
である。セル・サイズをさらに縮小すると、さらに改善
が達成できる。The total δR / R of the magnetic layers 24, 28 is used. For example, NiFe (90 °) / Cu (20 °) /
NiFe (70 °) / MnFe (120 °)
Assume a typical spin valve structure with δR / R 3.6% and R 20 Ω / cm 2 . 1μm width, 5μ length
m, the signal level is about 18 mV for a storage element with a sense current of 5 mA. This value performs fast real-time detection,
And it is sufficient for use in a 1 megabit storage device. Further improvements can be achieved by further reducing the cell size.

【００２１】本発明では、バルクハウゼン雑音の問題や
線形性の要件はない。高い異方性／保磁力をもつＣｏや
他のＣｏ合金などの材料により、記憶素子の安定性を強
化すると共に、感度を２倍または３倍に増大することが
できる。In the present invention, there is no Barkhausen noise problem or linearity requirement. Materials with high anisotropy / coercivity, such as Co and other Co alloys, can enhance the stability of the storage element and increase the sensitivity by a factor of two or three.

【００２２】図５は、本発明を実施する２×２記憶アレ
イ４０で読取りおよび書込み動作を実施するための記憶
セル選択回路を示す。図のように、アレイ４０は、４つ
の同じ記憶セル５０Ａ、５０Ｂ、５０Ｃ、５０Ｄと、２
つのセンス増幅器５１Ｘ、５１Ｙを備えている。各記憶
セル５０ＡないしＤは、活動ＭＲ記憶素子５２と参照Ｍ
Ｒ記憶素子５３を備えており、差分出力を生成する。ア
レイにおける信号の分岐を防ぐために、各記憶素子５
２、５３は２組のスイッチで付勢される。たとえば、記
憶セル５０Ａに書き込むには、記憶セル５０Ａのスイッ
チ５５とスイッチ５７を閉じて線Ｂ１と線Ｗ１を接続す
ると、ＭＲ記憶素子５２中を流れる書込み電流（図３の
３２）が横磁界を誘導することができる。また、書込み
線Ｗ１Sを大地に接続すると、流れる電流が縦磁界を誘
導することができる。記憶セル５０Ａの内容を読み出す
には、記憶セル５０Ａのスイッチ５５とスイッチ５７を
閉じて線Ｂ１と線Ｗ１を接続し、さらに記憶セル５０Ａ
のスイッチ５４とスイッチ５６を閉じて線Ｂ１'と線Ｗ
１'を接続すると、記憶セル５０Ａの活動ＭＲ記憶素子
５２と参照ＭＲ記憶素子５３の両方にセンス電流が流入
することができる。これらの記憶素子の差分出力が、セ
ンス増幅器５１Ｘによって差分出力電圧として感知され
る。FIG. 5 shows a storage cell selection circuit for performing read and write operations in a 2.times.2 storage array 40 embodying the present invention. As shown, the array 40 has four identical storage cells 50A, 50B, 50C, 50D, 2
And two sense amplifiers 51X and 51Y. Each storage cell 50A-D includes an active MR storage element 52 and a reference M
An R storage element 53 is provided to generate a difference output. Each storage element 5 is used to prevent signal divergence in the array.
2, 53 are energized by two sets of switches. For example, when writing to the memory cell 50A, the switch 55 and the switch 57 of the memory cell 50A are closed and the line B1 and the line W1 are connected, and the write current (32 in FIG. 3) flowing through the MR storage element 52 causes a transverse magnetic field. Can be guided. Further, connecting the write lines W1 S to ground, can current flow induces longitudinal field. To read the contents of the storage cell 50A, the switches 55 and 57 of the storage cell 50A are closed, the line B1 is connected to the line W1, and the storage cell 50A is further read.
Switch 54 and switch 56 are closed, and line B1 'and line W
When 1 ′ is connected, a sense current can flow into both the active MR storage element 52 and the reference MR storage element 53 of the storage cell 50A. The differential output of these storage elements is sensed by the sense amplifier 51X as a differential output voltage.

【００２３】したがって、記憶セル５０Ｂに書き込むに
は、記憶セル５０Ｂのスイッチ５５とスイッチ５４を閉
じてＷ２Sの書込み電流を活動化し、記憶セル５０Ｃに
書き込むには、記憶セル５０Ｃのスイッチ５５とスイッ
チ５９を閉じてＷ１Sの書込み電流を活動化することは
明らかであろう。他の場合についても同様である。記憶
セル５０Ｂの内容をセンス増幅器５１Ｙに読み出すに
は、記憶セル５０Ｂのスイッチ５５とスイッチ５７を閉
じて線Ｂ１と線Ｗ２を接続し、記憶セル５０Ｂのスイッ
チ５４とスイッチ５６を閉じて線Ｂ１'と線Ｗ２'を接続
する。記憶セル５０Ｃの内容をセンス増幅器５１Ｘに読
み出すには、記憶セル５０Ｃのスイッチ５５とスイッチ
５９を閉じて線Ｂ２と線Ｗ１を接続し、記憶セル５０Ｃ
のスイッチ５４とスイッチ５８を閉じて線Ｂ２'と線Ｗ
１'を接続する。このように、記憶セル５０ＡないしＤ
のうちの選択可能な１つに向けられる２つの磁界の組合
せによって、選択されたセルだけで切替えが誘導され
る。[0023] Thus, to write to the storage cells 50B, closing switch 55 and the switch 54 of the memory cells 50B activates the write current W2 S, to write to the cell 50C, a switch 55 of the cell 50C switch it will be apparent to activate the write current W1 S close 59. The same applies to other cases. To read the contents of the memory cell 50B to the sense amplifier 51Y, the switches 55 and 57 of the memory cell 50B are closed to connect the lines B1 and W2, and the switches 54 and 56 of the memory cell 50B are closed and the line B1 'is closed. And the line W2 '. To read the contents of the memory cell 50C to the sense amplifier 51X, the switches 55 and 59 of the memory cell 50C are closed, the lines B2 and W1 are connected, and the memory cell 50C is read.
Switch 54 and switch 58 are closed, and line B2 'and line W
Connect 1 '. Thus, the storage cells 50A to 50D
The combination of two magnetic fields directed to a selectable one of the above causes a switch to be induced in only the selected cell.

【００２４】図６は、図５に示したアレイ４０を実施す
る記憶装置６０を示す。アドレス・バス６４がアドレス
・デコーダ６２にアドレスを供給すると、アドレス・デ
コーダ６２は、選択されたワード線およびビット線のス
イッチを活動化し、アレイ４０中の記憶セル５０Ａない
しＤのうちの特定の１つが選択されるようになる。読取
り信号が読取り／書込み選択線６６を介して送られると
き、選択されたセルの内容が照会され、データ入出力装
置６８に移動され、後でデータ・バス７０に送られる。
読取り／書込み選択線６６を介して書込みコマンドを受
け取るとき、アドレス・デコーダ６２はスイッチを活動
化し、データ入出力６８の情報に従って選択された特定
のセルにデータを書き込むために、該セルに適切な書込
み電流を送る。FIG. 6 shows a storage device 60 implementing the array 40 shown in FIG. When the address bus 64 provides an address to the address decoder 62, the address decoder 62 activates the selected word line and bit line switches to activate a particular one of the storage cells 50A-D in the array 40. One will be selected. When a read signal is sent over the read / write select line 66, the contents of the selected cell are queried, moved to the data input / output device 68, and later sent to the data bus 70.
When receiving a write command via the read / write select line 66, the address decoder 62 activates the switch and applies the appropriate data to the selected cell in accordance with the information on the data input / output 68 to write the data to that particular cell. Send write current.

【００２５】[0025]

【図面の簡単な説明】[Brief description of the drawings]

【図１】最後に引用した従来技術のＭＲ記憶素子の"１"
および"０"情報状態を示す分解斜視図である。FIG. 1 shows the last cited prior art MR storage element "1"
FIG. 4 is an exploded perspective view showing a “0” information state.

【図２】最後に引用した従来技術のＭＲ記憶素子の"１"
および"０"情報状態を示す分解斜視図である。FIG. 2 shows the last cited prior art MR storage element “1”.
FIG. 4 is an exploded perspective view showing a “0” information state.

【図３】本発明を実施するＭＲ記憶素子の"１"および"
０"情報状態を示す分解斜視図である。FIG. 3 shows “1” and “1” of the MR storage element embodying the present invention.
It is an exploded perspective view showing a 0 "information state.

【図４】本発明を実施するＭＲ記憶素子の"１"および"
０"情報状態を示す分解斜視図である。FIG. 4 shows “1” and “1” of an MR storage element embodying the present invention.
It is an exploded perspective view showing a 0 "information state.

【図５】本発明の１つの実施態様を示す２ｘ２ＭＲ記憶
アレイの概略図である。FIG. 5 is a schematic diagram of a 2 × 2 MR storage array illustrating one embodiment of the present invention.

【図６】図５に示した記憶アレイを実施する記憶装置の
概略図である。FIG. 6 is a schematic diagram of a storage device implementing the storage array shown in FIG.

【符号の説明】[Explanation of symbols]

２０ 記憶素子 ２２ 基板 ２４ 第１の軟強磁性材料薄膜層 ２６ 非磁性金属材料薄膜層 ２８ 第２の強磁性材料薄膜層 ３０ 反強磁性層 ３２ 縦書込み電流 ３４ 書込み線 ３６ 横書込み／センス電流 ４０ アレイ ５０ 記憶セル ５１ センス増幅器 ５２ ＭＲ記憶素子 ５５ スイッチ ６２ アドレス・デコーダ ６４ アドレス・バス ６６ 読取り／書込み選択線 ６８ データ入出力装置 ７０ データ・バス REFERENCE SIGNS LIST 20 storage element 22 substrate 24 first soft ferromagnetic material thin film layer 26 nonmagnetic metal material thin film layer 28 second ferromagnetic material thin film layer 30 antiferromagnetic layer 32 vertical write current 34 write line 36 horizontal write / sense current 40 Array 50 Storage cell 51 Sense amplifier 52 MR storage element 55 Switch 62 Address decoder 64 Address bus 66 Read / write select line 68 Data input / output device 70 Data bus

───────────────────────────────────────────────────── フロントページの続き (72)発明者 デニー・ドゥアン＝リー・タン アメリカ合衆国95070 カリフォルニア 州サラトガ カニンガム・プレース 20407 (72)発明者 ワン・ポー・カン アメリカ合衆国95120 カリフォルニア 州サンノゼ シャドウ・ブルック・ドラ イブ 1007 (56)参考文献 特開 平６−84347（ＪＰ，Ａ) 特開 平５−266651（ＪＰ，Ａ) ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Denny Duan-Lee Than United States 95070 Saratoga, California Cunningham Place 20407 (72) Inventor Wang Po Khan United States 95120 San Jose, California Shadow Brook Drive 1007 (56) References JP-A-6-84347 (JP, A) JP-A-5-266651 (JP, A)

Claims (7)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】一の基板と、一の非磁性金属層によって分
離された２つの強磁性層を含む、前記基板上に付着され
た長方形の多層構造とを備えた非揮発性磁気抵抗記憶素
子であって、前記２つの強磁性層の磁化容易軸が前記記
憶素子のほぼ長さ方向にそれぞれ配向され、前記２つの
強磁性層のうち一方の強磁性層の磁化が前記記憶素子の
ほぼ長さ方向である１つの方向に固定され、前記２つの
強磁性層のうち他方の強磁性層の磁化が、印加される磁
界に応じて、前記固定された１つの方向に対してほぼ平
行な方向とほぼ反平行な方向との間で自由に切り替わ
り、さらに交換結合によって、前記一方の強磁性層を前
記固定された１つの方向に磁化させる反強磁性層を含む
ことを特徴とする、前記記憶素子。1. A non-volatile magnetoresistive storage element comprising: a substrate; and a rectangular multilayer structure deposited on said substrate, comprising two ferromagnetic layers separated by a nonmagnetic metal layer. Wherein the easy axes of magnetization of the two ferromagnetic layers are oriented substantially in the length direction of the storage element, and the magnetization of one of the two ferromagnetic layers is substantially equal to the length of the storage element. is fixed to one direction is the direction, the magnetization of the other ferromagnetic layer of the two ferromagnetic layers, in accordance with an applied magnetic field, a direction substantially parallel to the fixed one direction And an antiferromagnetic layer that switches freely between a direction substantially parallel to the antiferromagnetic layer and that magnetizes the one ferromagnetic layer in the fixed one direction by exchange coupling. element. 【請求項２】各々が請求項１で定義される種類の一の活
動記憶素子をそれぞれ備える複数のスピン・バルブ・セ
ルと、前記複数のセルのうち選択された１つのセル内に
ある活動記憶素子に横書込み電流を供給して横磁界を誘
導するのと同時に、前記選択されたセルに縦書込み電流
を供給して縦磁界を誘導することによって、前記活動記
憶素子の前記２つの強磁性層の磁化方向がほぼ平行であ
るかまたはほぼ反平行であるかに応じて、前記選択され
たセルに「１」または「０」を書き込む手段とを備える
ことを特徴とする、非揮発性磁気抵抗記憶アレイ。2. A plurality of spin valve cells each comprising an active storage element of the type defined in claim 1, and an active memory in a selected one of said plurality of cells. The two ferromagnetic layers of the active storage element are provided by supplying a lateral write current to the element to induce a transverse magnetic field and simultaneously supplying a vertical write current to the selected cell to induce a longitudinal magnetic field. Means for writing "1" or "0" to the selected cell depending on whether the magnetization direction of the cell is substantially parallel or substantially antiparallel. Storage array. 【請求項３】前記選択されたセル内にある活動記憶素子
に追加の横書込み電流を供給して安定性を増すため、前
記基板と他の層との間に挿入され且つ前記記憶素子を通
して当該記憶素子の長さ方向に延びる、別個の導体を含
むことを特徴とする、請求項２に記載の非揮発性磁気抵
抗記憶アレイ。3. An active storage element in the selected cell is inserted between the substrate and another layer and provided through the storage element to provide additional lateral write current to increase stability. 3. The non-volatile magnetoresistive storage array of claim 2 , comprising a separate conductor extending the length of the storage element . 【請求項４】各々が請求項１で定義される種類の一の活
動記憶素子と一の参照記憶素子をそれぞれ備える複数の
スピン・バルブ・セルと、 少なくとも１つの差分増幅器と、 前記複数のセルのうち選択された１つのセル内にある活
動記憶素子および参照記憶素子を介して関連する差分増
幅器にセンス電流を供給して、前記選択されたセルのそ
の時点の磁気状態を示す大きさの差分出力電圧を提供す
る手段とを備えることを特徴とする、非揮発性磁気抵抗
記憶アレイ。4. A plurality of spin valve cells each comprising one active storage element and one reference storage element of the type defined in claim 1 , at least one difference amplifier, and the plurality of cells. Providing a sense current to an associated difference amplifier via an active storage element and a reference storage element in a selected one of the cells to provide a difference of magnitude indicative of a current magnetic state of the selected cell. Means for providing an output voltage. 【請求項５】所望の１つのセルにデータを記憶するた
め、前記センス電流の方向に直交する方向に流れる書込
み電流を前記所望の１つのセルに印加するのと同時に、
前記所望のセル内にある活動記憶素子だけに前記センス
電流を供給する手段を含むことを特徴とする、請求項４
に記載の非揮発性磁気抵抗記憶アレイ。5. A method for storing data in a desired one cell while applying a write current flowing in a direction orthogonal to a direction of the sense current to the desired one cell,
5. The apparatus according to claim 4 , further comprising means for supplying said sense current only to active storage elements in said desired cell.
3. The nonvolatile magnetoresistive storage array according to claim 1. 【請求項６】前記センス電流で横磁界を誘導し、前記書
込み電流で縦磁界を誘導することによって、前記選択さ
れたセル内にある活動記憶素子の前記２つの強磁性層の
磁化方向がほぼ平行であるかまたはほぼ反平行であるか
に応じて、前記選択されたセルに「１」または「０」を
書き込むことを特徴とする、請求項４に記載の非揮発性
磁気抵抗記憶アレイ。6. A magnetic field induced by the sense current and a vertical magnetic field induced by the write current, whereby the magnetization directions of the two ferromagnetic layers of the active storage element in the selected cell are substantially changed. 5. The non-volatile magnetoresistive storage array of claim 4 , wherein "1" or "0" is written to the selected cell depending on whether it is parallel or nearly anti-parallel. 【請求項７】各々が一の基板と、一の非磁性金属層によ
って分離された２つの強磁性層を含む多層構造とをそれ
ぞれ備える複数の磁気抵抗記憶素子であって、各記憶素
子内にある前記２つの強磁性層の磁化容易軸が、前記記
憶素子のほぼ長さ方向で且つ印加されるセンス電流の方
向にほぼ平行に配向され、前記２つの強磁性層のうち一
方の強磁性層の磁化方向が記憶素子のほぼ長さ方向であ
る方向に固定され、前記２つの強磁性層のうち他方の強
磁性層の磁化方向が、前記一方の強磁性層の磁化方向に
対してほぼ平行またはほぼ反平行である２つのディジタ
ル状態の間で自由に切り替わり、さらに交換結合によっ
て、前記一方の強磁性層を前記固定された１つの方向に
磁化させる反強磁性層を含み、各記憶素子の幅がその長
さよりも、前記他方の強磁性層を前記２つのディジタル
状態のうち選択された１つの状態のままにしておく量だ
け短い、前記複数の磁気抵抗記憶素子と、データを書き
込むために、書込み電流を生成して、前記複数の磁気抵
抗記憶素子のうち選択された１つの記憶素子を前記２つ
のディジタル状態の一方から反対の状態に切り替える手
段と、 前記選択された記憶素子内のデータを読み取るために、
前記センス電流を印加して、前記選択された記憶素子内
にその時点で存在する状態を感知する手段とを備えるこ
とを特徴とする、非揮発性磁気抵抗記憶装置。7. A plurality of magnetoresistive storage elements each comprising one substrate and a multilayer structure including two ferromagnetic layers separated by one nonmagnetic metal layer, wherein each storage element has The easy axes of the two ferromagnetic layers are oriented substantially in the length direction of the storage element and substantially parallel to the direction of the applied sense current, and one of the two ferromagnetic layers is magnetization direction is fixed in a direction that is substantially longitudinal direction of the storage element, said two magnetization direction of the other ferromagnetic layer of the ferromagnetic layer is substantially parallel to the magnetization direction of the one ferromagnetic layer Or switch freely between two digital states that are almost antiparallel, and further by exchange coupling.
To move the one ferromagnetic layer in the fixed one direction.
Includes an antiferromagnetic layer to magnetize than the width a length of each of the memory elements, it remains a manner you Ku of one state selected among the other ferromagnetic layer the two digital states <br Generating a write current to write data to the selected one of the plurality of magnetoresistive storage elements to store the selected one of the plurality of magnetoresistive storage elements in the two digital states; Means for switching from one side to the opposite state, and for reading data in the selected storage element,
Means for applying the sense current to sense a state currently present in the selected storage element.
JP6022669A 1993-02-23 1994-02-21 Magnetoresistance storage element, array and device Expired - Fee Related JP2784439B2 (en)

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US08/021,413 US5343422A (en) 1993-02-23 1993-02-23 Nonvolatile magnetoresistive storage device using spin valve effect

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JPH06295419A JPH06295419A (en) 1994-10-21
JP2784439B2 true JP2784439B2 (en) 1998-08-06

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